The present invention relates to an actuator, and, more particularly, to an actuator for driving small, light weight mechanisms with several degrees of freedom, such as robot hands, manipulators, etc.
In, for example, British Pat. No. 1,554,738, one type of actuator for driving a load, in which a shape memory material is employed is disclosed, wherein the shape memory material is a coil spring and a further spring, arranged in alignment with the coil spring, imparts a deformation thereto are usually arranged in alignment, and a position is controlled by a balance between the reaction of the spring and the reaction of the shape memory material that changes with temperature. To construct a actuator which produces a large output, however, it is necessary to employ a shape memory material with a large wire diameter. This, however, results in a reduced heat-radiating performance of the shape memory material, and makes it difficult to increase the operating speed of the actuator in a cooling step.